This invention relates to the production of pH enhanced foodstuffs, especially pH enhanced comminuted meats. The invention includes a method of producing pH enhanced foodstuffs, and an apparatus and method for treating foodstuffs after pH enhancement.
It may be desirable or helpful in processing a foodstuff to increase the pH of the foodstuff over that naturally found in the material. A foodstuff that has been treated to exhibit an increased pH may be referred to as a pH enhanced foodstuff. For example, U.S. Pat. No. 5,871,795 discloses an apparatus and process for adding ammonia gas to unfrozen meat products to produce a pH enhanced meat product. U.S. Pat. No. 6,142,067 discloses another method and apparatus for applying ammonia gas or aqueous ammonia to comminuted meat to provide a uniformly elevated pH in the treated product. The system shown in U.S. Pat. No. 6,142,067 first adds ammonia gas or aqueous ammonia to an initial comminuted meat, and then comminutes the meat to distribute the added ammonia throughout the meat and drive the ammonia into the material.
One of the limitations on enhancing the pH of a foodstuff is the objectionable odor that may remain in the foodstuff after treatment. This is particularly true when relatively large pH adjustments are made using ammonia. U.S. Pat. No. 6,142,067 addresses the problem of ammonia odor in the treated meat by comminuting the meat after contact with ammonia. This further comminution has been found to help distribute the ammonia in the foodstuff. It is also believed that the pressure applied in comminution helps drive the ammonia into the foodstuff. In any event, the method of further comminuting a previously comminuted meat that has been exposed to ammonia has been found to reduce or eliminate the objectionable ammonia odor in many cases.
U.S. Pat. No. 5,871,795 discloses adding a pH reducing material such as carbon dioxide gas after the ammonia gas treatment. The added carbon dioxide tends to displace free ammonia remaining after the earlier treatment and thus reduce any ammonia odor. However, the carbon dioxide gas treatment disclosed in U.S. Pat. No. 5,871,795 is performed on the unfrozen meat and reduces the pH of the treated material.
It may be advantageous in certain circumstances to maintain a relatively high pH in a pH enhanced foodstuff. However, it is desirable to achieve this relatively high pH without any detrimental effects from the pH increasing material. In particular, it is desirable to use ammonia to produce pH enhanced foodstuffs having a relatively large pH adjustment, but with little or no objectionable ammonia odor.
The present invention provides a pH enhanced foodstuff production method that eliminates or reduces the odor of the pH increasing material in the treated product. This reduction or elimination of odors from the pH increasing material is accomplished without substantially affecting the pH of the treated product.
The method of producing a pH enhanced foodstuff according to the invention includes increasing the pH of an initial foodstuff, preferably by placing an initial foodstuff in contact with ammonia gas or aqueous ammonia and applying mechanical action to the material. After the pH adjustment, the method includes reducing at least the surface temperature of the pH enhanced foodstuff to below the freezing temperature of the pH enhanced foodstuff. The method then includes placing the fully frozen or partially frozen pH enhanced foodstuff in contact with carbon dioxide gas while maintaining the surface temperature of the pH enhanced foodstuff below the freezing temperature of the material.
As used in this disclosure and the accompanying claims the xe2x80x9cfreezing temperaturexe2x80x9d of the foodstuff refers to the initial freezing temperature at which ice crystals begin to form in the material. A foodstuff in which substantially all unbound water is in crystalline form will be referred to as a xe2x80x9cfully frozenxe2x80x9d foodstuff. This fully frozen foodstuff is to be distinguished from a foodstuff that has its entire volume at a temperature just below the freezing temperature of the foodstuff. In this latter case, ice crystals will be present, but substantial amounts of liquid free water may be present in the material. A foodstuff in such a condition will be referred to as a xe2x80x9cthoroughly frozenxe2x80x9d foodstuff in this disclosure. A xe2x80x9cpartially frozenxe2x80x9d foodstuff will refer to a foodstuff that has its surface at a temperature below the freezing temperature of the material, while the interior temperature may still be above the freezing temperature.
Rather than a complete pH enhanced foodstuff production process, the invention may be applied as a treatment for pH enhanced foodstuffs that have already undergone pH enhancement. Whether the process is defined as a process of producing pH enhanced foodstuffs or a process of treating previously produced pH enhanced foodstuffs, the invention is particularly useful in producing pH enhanced comminuted meats and defatted meats that may be mixed with other materials to make a final product.
The preferred form of the invention applied to comminuted foodstuffs includes forming the pH enhanced foodstuff into relatively small pieces or units of fully frozen or partially frozen material prior to the carbon dioxide gas contacting step. These frozen or partially frozen units are then preferably mixed together or otherwise agitated in a carbon dioxide gas atmosphere to provide the desired carbon dioxide contact.
The apparatus for treating pH enhanced foodstuffs according to invention includes a mixing vessel which houses at least one agitating or mixing element driven by a suitable drive device. The mixing vessel includes a carbon dioxide inlet connected to a carbon dioxide supply. Carbon dioxide may be added in gaseous form or as solid carbon dioxide pellets or chips which sublime to form carbon dioxide gas in the mixing vessel.
The present invention facilitates the elimination or reduction of pH increasing material odor in the frozen pH enhanced foodstuff, but does not significantly reduce the pH of the foodstuff. Thus, the pH enhanced foodstuff may be taken to relatively high pH levels with gaseous or aqueous ammonia and may be maintained at that relatively high pH level, without producing the objectionable ammonia odor. This pH enhanced foodstuff may then be mixed with other materials or otherwise used to form a final product.
These and other objects, advantages, and features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.